Energy management for multiple charging stations

ABSTRACT

In order to ensure reliable power for charging electric vehicles is available at each charging station at a charging site having multiple charging stations, the systems and methods disclosed herein provide for charge transfers between batteries of such charging stations. A plurality of charging stations at a charging site are connected via a direct current (DC) bus in order to transfer energy between the charging stations, such as to balance the energy stored at the respective batteries of the charging stations. Each charging station includes a system controller controlling operation of the charging station and a DC bus connection to provide DC current from the battery to the DC bus and to provide DC current from the DC bus to the battery, as controlled by the system controller. A centralized management system may also communicate with and control aspects of operation of the respective system controllers of the charging stations.

TECHNICAL FIELD

At least one aspect generally relates to improvements to vehiclecharging stations generally and more particularly to improvements inenergy management and charge transfer between multiple vehicle chargingstations at a charging site.

BACKGROUND

Charging stations provide electric power to electric vehicles (EVs),including plug-in hybrid vehicles, that can operate without the use orwith limited use of hydrocarbon-based fuels. Installation ofconventional charging stations typically requires improvements toinfrastructure including upgrades to electrical service and constructionof suitable housing. The costs, planning, and time required to installthese charging systems can be a deterrent to potential commercial orresidential operators. To reduce the installation and operatingrequirements associated with traditional charging stations, somecharging stations include batteries to store energy received from apower source (such as an electric utility power grid) over an extendedtime interval. At charging sites having multiple charging stations,different rates of utilization of the charging stations often results insome charging stations have more energy stored in their batteries thanothers. For example, drivers frequently park and charge at the chargingstations nearest a location of interest (e.g., an entrance to abusiness), resulting in higher rates of battery discharging for suchcharging stations. Since the batteries of the charging stations aredischarged during vehicle charging at a faster rate than they arecharged from the power source, however, the batteries of the morefrequently used charging stations may be depleted more quickly than thebatteries of charging stations that are less frequently used. Driverfrustration resulting from the inability to charge at charging stationswith depleted batteries or from slow charging at such charging stationshas a detrimental impact on adoption of electric and charging hybridvehicles. Therefore, improved techniques for ensuring reliable power atcharging stations using batteries to store charge are needed in generaland in particular for charging sites having multiple charging stations.

SUMMARY

The systems, methods, and computer-readable instructions disclosedherein solve the problem of ensuring reliable power for each of theelectric vehicle charging stations at a charging site having multipleelectric vehicle chargers through charge transfers between such electricvehicle chargers. As described herein, a vehicle charging system forcharging a vehicle is provided, the vehicle charging system comprising:a power input port configured to receive input electric power from apower source; a battery configured to receive and store electric powerderived from the input electric power received at the power input port;a vehicle coupling configured to receive a charging current from thebattery and to provide an electrical interconnect between the vehiclecharging system and the vehicle in order to provide the charging currentto the vehicle; an inter-charger connection communicatively connected tothe battery and configured to provide a direct current (DC) output to anaddition vehicle charging system and to receive a DC input from theadditional vehicle charging system via a direct connection with theadditional vehicle charging system; and a system controller comprisingone or more processors configured to control charge transfers. Thesystem controller is configured to control charge transfers bydetermining occurrence of a triggering condition for charge transferbetween the battery of the vehicle charging system and an additionalbattery of the additional vehicle charging system via the directconnection and, in response to determining occurrence of the triggeringcondition, controlling the vehicle charging system to effect the chargetransfer based upon the triggering condition. The charge transfer may beeffect by either (i) providing the DC output from the battery to theadditional vehicle charging system via the inter-charger connection or(ii) receiving and charging the battery with the DC input from theadditional charging system via the inter-charger connection.

The input electric power may be an alternating current (AC) inputelectric power, while the energy storage current is a DC energy storagecurrent. The direct connection may be a DC bus connecting a plurality ofvehicle charging systems at a vehicle charging site, including thevehicle charging system and the additional vehicle charging system, inwhich case the inter-charger connection will be a DC bus connection. Insome such embodiments, the DC bus further connects an external batteryto the vehicle charging system, such that the DC bus connection isconfigured to provide the DC output to the external battery connected tothe DC bus and to receive the DC input from the external battery. Thesystem controller may likewise be configured to determine occurrence ofa triggering condition for charge transfer between the battery of thevehicle charging system and the external battery via the DC bus and, inresponse to determining occurrence of the triggering condition, controlthe vehicle charging system to effect a charge transfer with theexternal battery based upon the triggering condition. Such chargetransfer may be effected by either (i) providing the DC output from thebattery to the external battery via the DC bus connection or (ii)receiving and charging the battery with the DC input from the externalbattery via the DC bus connection.

In some embodiments, the vehicle charging system further comprises apower conversion circuit configured to convert the input electric powerinto an energy storage current used to charge the battery. In some suchembodiments, the power conversion circuit is further configured (i) toreceive a DC current from the battery and provide the charging currentto the vehicle coupling using the DC current and (ii) to connect thebattery to the inter-charger connection.

The triggering condition may comprise various conditions, which may beseparately or collectively determinative of a situation in which acharge transfer should occur. In some embodiments, the triggeringcondition is based at least in part upon a charge level of the batteryand an additional charge level of the additional battery of theadditional charging system. An indication of the additional charge levelmay be received in an electronic message received from the additionalcharging system. In further embodiments, the triggering condition isbased at least in part upon a charge imbalance between a charge level ofthe battery of the vehicle charging system and an additional chargelevel of the additional battery of the additional charging systemexceeding a threshold charge differential. In some such embodiments, thethreshold charge differential is dynamically based upon one or more ofthe following charging site conditions: current availability of theinput electric power from the power source, predicted futureavailability of the input electric power from the power source, currentcharging demand for each of the vehicle charging system and theadditional vehicle charging system, predicted future demand for each ofthe vehicle charging system and the additional vehicle charging system,or operational statuses of the vehicle charging system and theadditional vehicle charging system. In still further embodiments, thetriggering condition comprises a discharge imbalance between thecharging current provided by the vehicle coupling of the vehiclecharging system and an additional charging current of an additionalvehicle coupling of the additional charging system exceeding a thresholddischarge differential over a predetermined time interval.

In some embodiments, the triggering condition comprises receiving acommand from a centralized management system communicatively connectedto the vehicle charging system and the additional vehicle chargingsystem via a communication network. The centralized management systemmay generate and send such command based upon any of the variousconditions described above. In order to facilitate detection of suchconditions, the centralized management system may obtain operating datafrom each of a plurality of vehicle charging systems at a charging site.In some embodiments, the centralized management system may furtherobtain an indication of a demand level for the power source, in order todetermine whether the demand level exceeds a threshold demand level. Insome embodiments, the centralized management system may communicate witha plurality of vehicle charging systems at a charging site to bothreceive operating data and to send commands to control each of theplurality of vehicle charging systems to effect a determined chargetransfer. In further embodiments, the centralized control system mayfurther communicate with one or more external batteries or externalbattery systems connected to the plurality of vehicle charging systemsat the charging site.

Methods or computer-readable media storing instructions for implementingall or part of the vehicle charging system described above may also beprovided in some aspects in order to provide or operate a vehiclecharging station. Additional or alternative features described hereinbelow may be included in some aspects.

According to one such aspect, a method for managing energy transfersbetween a plurality of vehicle charging systems as described abovedisposed at a charging site is provided, the method comprising: charginga battery of a vehicle charging system and an additional battery of anadditional vehicle charging system at the charging site using an inputelectric power from a power source; determining occurrence of atriggering condition for charge transfer between the battery of thevehicle charging system and the additional battery of the additionalvehicle charging system via a direct connection between the vehiclecharging system and the additional vehicle charging system; and inresponse to determining occurrence of the triggering condition,controlling the vehicle charging system to effect the charge transferbased upon the triggering condition. The charge transfer may be effectedby either (i) providing a DC output from the battery to the additionalvehicle charging system via an inter-charger connection of the vehiclecharging system or (ii) receiving and charging the battery with a DCinput from the additional charging system via the inter-chargerconnection, wherein the inter-charger connection is communicativelyconnected to the battery and configured to provide the DC output to theaddition vehicle charging system and to receive the DC input from theadditional vehicle charging system via the direct connection with theadditional vehicle charging system.

According to another such aspect, a site charging system for chargingvehicles at a charging site is provided, the site charging systemcomprising: a plurality of vehicle charging systems as described abovedisposed at the charging site connected via a DC bus; and a centralizedmanagement system communicatively connected to the plurality of vehiclecharging systems via an electronic communication connection, comprisingone or more processors configured to: determine occurrence of atriggering condition for charge transfer between the respectivebatteries of a first vehicle charging system and a second vehiclecharging system of the plurality of vehicle charging systems via the DCbus, and, in response to determining occurrence of the triggeringcondition, control (i) the first vehicle charging system to provide DCpower to the DC bus from the battery of the first vehicle chargingsystem and (ii) the second vehicle charging system to charge the batteryof the second vehicle charging system using the DC power from the DCbus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a block diagram of an example of a charging siteconfigured for energy management between multiple vehicle chargingsystems via a DC bus in accordance with certain aspects disclosedherein.

FIG. 1B illustrates a block diagram of an example of an electric vehiclecharging system configured for DC charge transfer in accordance withcertain aspects disclosed herein.

FIGS. 2A-B illustrate block diagrams of examples of a charging siteconfigured for energy management between multiple vehicle chargingsystems via a local AC circuit in accordance with certain aspectsdisclosed herein.

FIG. 2C illustrates a block diagram of an example of an electric vehiclecharging system configured for AC charge transfer in accordance withcertain aspects disclosed herein.

FIG. 3 illustrates a block diagram of an example of a combined electricvehicle charging system configured for both AC and DC charge transfer inaccordance with certain aspects disclosed herein.

FIG. 4 illustrates a block diagram illustrating a simplified example ofa hardware implementation of a controller in accordance with certainaspects disclosed herein.

FIG. 5 illustrates a flow diagram of an example energy management methodfor monitoring a charging site and controlling charge transfers betweenmultiple vehicle charging stations in accordance with certain aspectsdisclosed herein.

FIG. 6 illustrates a flow diagram of an example charge balancing methodfor determining charge imbalance and charge transfers between multiplevehicle charging stations to implement certain aspects of the exampleenergy management method of FIG. 5 in accordance with certain aspectsdisclosed herein.

DETAILED DESCRIPTION

The techniques disclosed herein generally relate to solving the problemof ensuring reliable power for each of the charging stations at acharging site having multiple electric vehicle chargers. In order tofacilitate energy transfers between batteries of the multiple chargingstations at the charging site, one or more of a local alternatingcurrent (AC) circuit or a direct current (DC) bus is provided at thecharging site and connected to each of the charging stations. Eachcharging station is configured to transfer electric power via one orboth of the local AC circuit or the DC bus. The charging stations thusinclude at least one of a bidirectional inverter controllable by asystem controller to provide or receive AC power via the local ACcircuit or a DC bus connection controllable by the system controller toprovide and receive DC power via the DC bus at the charging site. Bytransferring charge between charging stations at the charging site,charge imbalances between batteries of the charging stations may bereduced or eliminated, thereby ensuring each of the charging stationshas sufficient power to charge vehicles. Additional or alternativefeatures are described in further detail below.

Several aspects of electric vehicle (EV) or plug-in hybrid vehiclecharging systems and related charging site systems will now be presentedwith reference to various embodiments. Although described herein asrelating to EVs, it should be understood that the techniques may beapplied equally to plug-in hybrid vehicles or other wholly or partiallybattery-powered devices that may be charged by a high-voltage orhigh-power charging station. Charging stations are used for rechargingbatteries in EVs by supplying AC or DC power to EVs. In turn, thecharging stations receive an electric power supply from a utility powergrid connection or local power source (e.g., solar, wind, water, orhydrocarbon-powered power generation systems). Some charging stationsmay store power in one or more internal or connected batteries in orderto smooth power consumption over time. In addition to using such storedpower to charge EVs, charging stations may further provide such storedpower to other charging stations disposed at the same charging site,thereby enabling efficient use of the power stored at multiple chargingstations to charge EVs at any of the charging stations. In someembodiments, such charge sharing between charging stations at a chargingsite further enables charging EVs without an active connection to autility power grid or other power source.

FIG. 1A illustrates a block diagram of an example of a charging site 10configured for energy management between multiple EV charging systems100A-D via a DC bus 101. The charging site 10 is supplied with AC powerfrom an electric power grid 20 via a site meter 22, which records powerconsumption and connects the various electrical components disposed atthe charging site 10 to the electric power grid 20. Thus, the electricpower grid 20 provides AC power to each of the EV charging systems100A-D and other electrical components via the site meter 22, includingproviding AC power to a non-charging load 24 (e.g., commercial buildingelectrical infrastructure) at the charging site 10. In some embodiments,the site meter 22 is a smart meter including additional control logicand communication functionality. For example, the site meter 22 may beconfigured to communicate with one or more external servers (not show)and/or the centralized management system 150 to obtain demand dataregarding load on or demand charges for AC power from the electric powergrid 20. In some such embodiments, the site meter 22 may be configuredto disconnect part or all of the loads from the electric power grid 20upon the occurrence of certain conditions (e.g., during peak hours orwhen the power grid is unstable due to high demand). In this way, thesite meter 22 may be used to separate the charging site 10 from theelectric power grid 20 when needed. Although only one site meter 22 isshown, some embodiments may include a plurality of meters, each of whichmay perform part or all of the operation of the site meter 22. Suchembodiments may be implemented to facilitate more targeted control ofoperations of individual EV charging systems 100 or non-charging loads24 at the charging site 10.

The AC power from the site meter 22 is provided as an input AC electricpower to the respective input ports 102A-D of the EV charging systems100A-D via one or more wired AC connections. In some embodiments, theinput AC electric power is received at each of the input ports 102A-D asa 120V or 240V single-phase or three-phase AC power supply. As discussedelsewhere herein, each of the EV charging systems 100A-D converts andstores such input AC electric power to DC power stored in batteries ofrespective energy storage modules 114A-D, from which charging currentsmay be provided to vehicles via vehicle couplings 132A-D of the EVcharging systems 100A-D. The EV charging systems 100A-D are controlledby respective system controllers 120A-D, which monitor operating data ofthe respective EV charging systems 100A-D and control charging anddischarging of the energy storage modules 114A-D.

In some embodiments, the DC power may be stored in the energy storagemodules 114A-D over an interval of time in order to provide chargingcurrent to EVs via respective vehicle couplings 132A-D at a faster ratethan the input AC electric power is received by the EV charging systems100A-D. While this has significant advantages in reducing the electricalinfrastructure requirements for the charging site 10, some of the EVcharging systems 100A-D may be used more that others. For example, EVcharging systems 100C and 100D may experience greater use due to closerproximity to a destination (e.g., by being located in a parking lot atlocations nearer an entrance to a commercial building). As illustrated,vehicles 140C and 140D may be connected to EV charging systems 100C and100D by vehicle couplings 132C and 132D, respectively, in order toreceive charging currents from energy stored in the energy storagemodules 114C and 114D, while no vehicles are charging at EV chargingsystems 100A and 100B. Thus, the batteries of EV charging systems 100Cand 100D will discharge faster than those of EV charging systems 100Aand 100B, resulting in a charge imbalance among the energy storagemodules 114A-D. To address such an imbalance, energy may be transferredfrom EV charging systems 100A and 100B to EV charging systems 100C and100D via the DC bus 101.

The DC bus 101 provides a direct DC power connection between the EVcharging systems 100A-D to enable charge transfers among the energystorage modules 114A-D. Each of the EV charging systems 100A-D includesan inter-charger connection (not shown) that provides a bidirectional DCconnection to the DC bus 101, and thereby to each of the other EVcharging systems 100A-D. Through such inter-charger connections, the EVcharging systems 100A-D are enabled to receive and to provide DC currentat various times as part of charge transfers, which may be used toperform charge balancing between the energy storage modules 114A-D. Insome embodiments, one or more external batteries 30 are also connectedto the DC bus 101 to store energy received from the EV charging systems100A-D and provide the stored energy at a later time, as needed. Suchexternal batteries 30 may include controllers (not shown) to controlcharging and discharging, or the external batteries 30 may be controlledby the system controllers 120A-D of the EV charging systems 100A-D or bya centralized management system 150. Similarly, in various embodiments,charge transfers may be determined and controlled by the systemcontrollers 120A-D of the EV charging systems 100A-D or by a centralizedmanagement system 150. To facilitate such control decisions, each of thesystem controllers 120A-D is connected via wired or wirelesscommunication connections with the other system controllers 120A-Dand/or with the centralized management system 150 to exchange electronicmessages or signals.

The centralized management system 150 may communicate with each of theEV charging systems 100A-D in order to monitor operating data regardingthe EV charging systems 100A-D and to determine and control chargetransfers as needed. The centralized management system 150 may belocated at the charging site 10 or at a location remote from thecharging site 10. When remote from the charging site 10, the centralizedmanagement system 150 may be communicatively connected to the EVcharging systems 100A-D via a network 40, which may be a proprietarynetwork, a secure public internet, a virtual private network, or someother type of network, such as dedicated access lines, plain ordinarytelephone lines, satellite links, cellular data networks, orcombinations of these. In various embodiments, the EV charging systems100A-D may be communicatively connected with the network 40 directly orvia a local router 42. In some embodiments in which the centralizedmanagement system 150 is located at the charging site 10, thecentralized management system 150 may be combined with or incorporatedwithin any of the EV charging systems 100A-D. In still furtherembodiments, the centralized management system 150 may be configured asa local cloud or server group distributed across the system controllers120A-D of the EV charging systems 100A-D in order to provide robustcontrol in the event of a network disruption.

In some embodiments, the centralized management system 150 may alsocommunicate with remote EV charging systems that are deployed inlocations remote from the charging site 10, which locations may beseparated by large geographic distances. For example, the centralizedmanagement system 150 may communicate with EV charging systems 100located in different parking facilities, on different floors of the sameparking structure, or in different cities. Such centralized managementsystem 150 may comprise one or more servers configured to receiveoperating data from and to send data and/or control commands to each ofthe EV charging systems 100A-D. To facilitate communication, thecentralized management system 150 may be communicatively connected tothe system controllers 120A-D of the EV charging systems 100A-D via anelectronic communication link with a communication interface module (notshown) within each of the EV charging systems 100A-D.

The centralized management system 150 may group or relate EV chargingsystems according to their location, their intended function,availability, operating status, and capabilities. The centralizedmanagement system 150 may remotely configure and control the EV chargingsystems, including the EV charging systems 100A-D. The centralizedmanagement system 150 may remotely enforce regulations or requirementsgoverning the operation of the EV charging systems 100A-D. Thecentralized management system 150 may remotely interact with users ofthe EV charging systems 100A-D. The centralized management system 150may remotely manage billing, maintenance, and error detection for eachof the EV charging systems 100A-D. For example, error conditionsresulting in manual disconnection of a vehicle from any of the EVcharging systems 100A-D may be reported by such EV charging system tothe centralized management system 150 for analysis. The centralizedmanagement system 150 may also communicate with mobile communicationdevices of users of the EV charging systems 100A-D, such as mobilecommunication devices or other computing devices used by operators ofthe EV charging systems 100A-D to enable the operator to self-configurethe EV charging systems 100A-D, charge pricing, language localization,currency localization, and so on. Operation of the centralizedmanagement system 150 in relation to charge transfers between the EVcharging systems 100A-D is further described elsewhere herein.

FIG. 1B illustrates a block diagram of an example of an EV chargingsystem 100 configured in accordance with certain aspects disclosedherein. The EV charging system 100 may be any of the EV charging systems100A-D at the charging site 10 illustrated in FIG. 1A. The EV chargingsystem 100 is configured to receive electric power from a power source(e.g., electric power grid 20) via an input port 102 or 104 in order tocharge an energy storage module 114 (e.g., one or more batteries), fromwhich the EV charging system 100 provides a charging current to avehicle 140 in order to charge a battery 148 of the vehicle 140. Suchcharge is provided through a vehicle coupling 132, which may comprise acharging cable utilizing one or more standard connector types (e.g.,Combined Charging System (CCS) or Charge de Move (CHaDEMO) connectors).In addition to being connected to one or more power sources via theinput ports 102 or 104, the EV charging system 100 includes a DC busconnection 160 to the DC bus 101 at the charging site 10. Through the DCbus connection 160, the EV charging system 100 is configured to send DCpower to one or more additional EV charging systems 100′ or 100″ and toreceive DC power from such additional EV charging systems 100′ or 100″,as controlled by a system controller 120 of the EV charging system 100.Although the illustrated EV charging system 100 is illustrated ascommunicating with a centralized management system 150, alternativeembodiments of the EV charging system 100 need not be configured forsuch external communication. Additional or alternative components andfunctionality may be included in further alternative embodiments ofcharging systems.

The EV charging system 100 includes a power input module 110 having oneor more circuits configurable to transform, condition, or otherwisemodify power received from an input port 102 or 104 to provideconditioned power to a power conversion module 112. The input powerreceived at input ports 102 or 104 may be received from an electricpower grid 20, a local power generator (e.g., a solar panel or a windturbine), or any other power source. In some embodiments, input AC poweris received at an AC input port 102, while input DC power is received ata DC input port 104 (e.g., from photovoltaic cells or other types of DCpower sources). The DC input port 104 may be connected to one or more ofan inverter module 106 or a power conditioning module 108 for the inputDC power. In further embodiments, DC current received via DC input port104 is converted to an AC current by an inverter module 106, and the ACcurrent is then provided to power input module 110. The power inputmodule 110 may combine AC or DC current received from multiple sources.Similarly, the power input module 110 may direct AC or DC currentreceived from multiple sources to individual circuits or sections of thepower conversion module 112. In some embodiments, the power input module110 may include a rectifier to convert AC current received at an inputport 102 or 104 into DC current to be provided to the power conversionmodule 112. In further embodiments, DC current received via DC inputport 104 may instead be provided to a power conditioning module 108 thatmay include voltage level converting circuits, filters, and otherconditioning circuits to provide a charging current to the energystorage module 114.

The power conversion module 112 includes some combination of one or moreAC-to-DC, DC-to-DC, and/or DC-to-AC converters for efficient conversionof AC or DC input power received from a power utility or other source atinput port 102 or 104 via the power input module 110 to a DC energystorage current 126 provided to the energy storage module 114, whichstores the power until needed to provide a charging current 116 to avehicle 140. In some embodiments, the power conversion module 112includes an AC-to-DC conversion circuit that generates a DC energystorage current 126 that is provided to an energy storage module 114.Alternatively, the power input module 110 may include an AC-to-DCconversion circuit to generate a DC current from an input AC electricpower. In further embodiments, the energy storage module 114 includeshigh-capacity batteries that have a storage capacity greater than amultiple of the storage capacity in the EVs to be charged (e.g., threetimes, five times, or ten times an expected vehicle battery capacity).The storage capacity of the energy storage module 114 may be configuredbased on the expected average charge per charging event, which maydepend upon factors such as the types of vehicles charged, the depletionlevel of the vehicle batteries when charging starts, and the duration ofeach charging event. For example, a retail parking site may have morecharging events of shorter duration, while a commuter train parking lotmay have fewer charging events of longer duration. In variousembodiments, the storage capacity of the energy storage module 114 maybe configured based on maximum expected charging offset by powerreceived from an electric utility. In some embodiments, the storagecapacity of each of the energy storage modules 114 of the EV chargingsystems 100 and any external batteries 30 at a charging site 10 may beconfigured to ensure a total charge stored at the charging site 10 issufficient for an expected maximum load due to vehicle charging. Infurther embodiments, the power received from an electric utility may belimited to power available during low-demand times, such as off-peak orlow-priced periods of the day. The power input module 110 may beconfigured to block or disconnect inflows of power during peak orhigh-priced periods of the day. In some embodiments, the power inputmodule 110 may be configured to enable power reception during peakperiods to ensure continued operation of the EV charging system 100 whenpower levels in the energy storage module 114 are unexpectedly low.

In some embodiments, the power conversion module 112 may include one ormore DC-to-DC conversion circuits that receive DC current 128 at a firstvoltage level from the energy storage module 114 and drive a chargingcurrent 116 to a vehicle 140 through a vehicle coupling 132 to supply avehicle 140 with the charging current 116 via a vehicle charge port 142.The vehicle coupling 132 serves as an electrical interconnect betweenthe EV charging system 100 and the vehicle 140. In various embodiments,such vehicle coupling 132 comprises a charging head and/or a chargingcable. For example, the vehicle coupling 132 may comprise a chargingcable having a standard-compliant plug for connection with a vehiclecharge port 142 of vehicles 140. The vehicle coupling 132 may includeboth a power connection for carrying the charging current 116 and acommunication connection for carrying electronic communication betweenthe charge controller 130 and the vehicle 140. In some embodiments, theEV charging system 100 may comprise multiple vehicle couplings 132, andthe power conversion module 112 may include a corresponding number ofDC-to-DC conversion circuits specific to each of the multiple couplings.According to some embodiments, the power conversion module 112 may befurther configured to receive a reverse current 118 from a vehicle 140via the vehicle coupling 132, which reverse current 118 may be used toprovide a DC energy storage current 126 to add energy to the energystorage module 114. In some examples, the power conversion module 112includes one or more inverters that convert the DC current 128 to an ACcurrent that can be provided as the charging current 116.

A charge controller 130 controls the charging current 116 and/or reversecurrent 118 through each vehicle coupling 132. To control charging ordischarging of the vehicle 140, the charge controller 130 comprises oneor more logic circuits (e.g., general or special-purpose processors)configured to execute charging control logic to manage charging sessionswith vehicle 140. Thus, the charge controller 130 is configured tocommunicate with the system controller 120 to control the powerconversion module 112 to provide the charging current 116 to the vehicle140 or to receive the reverse current 118 from the vehicle 140 via thevehicle coupling 132. In some instances, the charge controller 130 mayinclude power control circuits that further modify or control thevoltage level of the charging current 116 passed through the vehiclecoupling 132 to the vehicle 140. The charge controller 130 alsocommunicates via the vehicle coupling 132 with a vehicle chargecontroller 144 within the vehicle 140 to manage vehicle charging. Thus,the charge controller 130 communicates with the vehicle chargecontroller 144 to establish, control, and terminate charging sessionsaccording to EV charging protocols (e.g., CCS or CHaDEMO). The chargecontroller 130 may be communicatively connected with the vehiclecoupling 132 to provide output signals 134 to the vehicle chargecontroller 144 and to receive input signals 136 from the vehicle chargecontroller 144.

A system controller 120 is configured to control operations of the EVcharging system 100 by implementing control logic using one or moregeneral or special-purpose processors. The system controller 120 isconfigured to monitor and control power levels received by the powerinput module 110, power levels output through the charging current 116,energy levels in the energy storage module 114, and charge received fromor output to the DC bus 101 via the DC bus connection 160. The systemcontroller 120 is further configured to communicate with and controleach of the one or more charge controllers 130, as well as controllingthe power conversion module 112. For example, the system controller 120is configured to control the power conversion module 112 and the chargecontroller to supply a charging current 116 to the vehicle coupling 132in response to instructions from the charge controller 130. As discussedfurther herein, the system controller 120 is also configured to control(either separately or in coordination with the centralized managementsystem 150) charge transfers to manage energy levels of the EV chargingsystem 100 in relation to additional EV charging systems 100′ and 100″at the charging site 10.

The system controller 120 controls charge transfers by determiningoccurrence of a triggering condition for a charge transfer andcontrolling a response to such triggering condition in order to provideor receive DC power via a direct connection with one or more additionalEV charging systems 100′ or 100″ provided by the DC bus 101. Thus, thesystem controller 120 controls receiving DC input from and providing DCoutput to the DC bus 101 via a DC bus connection 160 of the EV chargingsystem 100 in order to effect charge transfers at the charging site 10.The DC bus connection 160 serves as an inter-charger connection of theEV charging system 100 and is configured to connect the EV chargingsystem 100 to the DC bus 101 at the charging site 10 as a directconnection for the exchange of DC power between the EV charging system100 and additional EV charging systems 100′ and 100″ (e.g., other EVcharging systems of the EV charging systems 100A-D) at the charging site10, as well as with any external batteries 30 at the site 10 (asillustrated in FIG. 1A). In some embodiments, the DC bus connection 160receives and provides DC power via a DC link 156 with the powerconversion module 112, with the power conversion module 112 beingcontrolled by the system controller 120 to manage any voltage or currentrequirements of the energy storage module 114 or the DC bus 101. Inadditional or alternative embodiments, the DC bus connection 160 maydirectly interface with the energy storage module 114 in order toprovide a DC output current 152 from the energy storage module 114 tothe DC bus 101 and to provide a DC input current 154 from the DC bus 101to the energy storage module 114, as controlled by the system controller120.

The system controller 120 is also configured to communicate with othervarious system components 138 of the EV charging system 100 (e.g., othercontrollers or sensors coupled to the energy storage module 114 or othercomponents of the EV charging system 100) in order to receive operatingdata and to control operation of the system via operation of such systemcomponents 138. For example, the system controller 120 may monitortemperatures within the EV charging system 100 using the systemcomponents 138 and may be further configured to mitigate increases intemperature through active cooling or power reductions using the same ordifferent system components 138. Likewise, the system controller 120communicates with a user interface module 122 (e.g., a touchscreendisplay) and a communication interface module 124 (e.g., a networkinterface controller) to provide information and receive controlcommands. Each communication interface module 124 may be configured tosend and receive electronic messages via wired or wireless dataconnections, which may include portions of one or more digitalcommunication networks.

The system controller 120 is configured to communicate with thecomponents of the EV charging system 100, including power input module110, power conversion module 112, the user interface module 122, thecommunication interface module 124, the charge controller 130, and thesystem components 138 over one or more data communication links. Thesystem controller 120 may also be configured to communicate withexternal devices, including a vehicle 140 via the vehicle coupling 132,one or more additional EV charging systems 100′ and 100″ via thecentralized management system 150, one or more external batteries 30, ora site meter 22. The system controller 120 may manage, implement orsupport one or more data communication protocols used to controlcommunication over the various communication links, including wirelesscommunication or communication via a local router 42. The datacommunication protocols may be defined by industry standards bodies ormay be proprietary protocols.

The user interface module 122 is configured to present informationrelated to the operation of the EV charging system 100 to a user and toreceive user input. The user interface module 122 may include or becoupled to a display with capabilities that reflect intended use of theEV charging system 100. In one example, a touchscreen may be provided topresent details of charging status and user instructions, includinginstructions describing the method of connecting and disconnecting avehicle 140. The user interface module 122 may include or be coupled toa touchscreen that interacts with the system controller 120 to provideadditional information or advertising. The system controller 120 mayinclude or be coupled to a wireless communication interface that can beused to deliver a wide variety of content to users of the EV chargingsystem 100, including advertisements, news, point-of-sale content forproducts/services that can be purchased through the user interfacemodule 122. The display system may be customized to match commercialbranding of the operator, to accommodate language options and for otherpurposes. The user interface module 122 may include or be connected tovarious input components, including touchscreen displays, physical inputmechanisms, identity card readers, touchless credit card readers, andother components that interact through direct connections or wirelesscommunications. The user interface module 122 may further support userauthentication protocols and may include or be coupled to biometricinput devices such as fingerprint scanners, iris scanners, facialrecognition systems and the like.

In some embodiments, the energy storage module 114 is provisioned with alarge battery pack, and the system controller 120 executes software tomanage input received from a power source to the battery pack based upondemand level data (e.g., demand or load data from an electric power grid20 or site meter 22), such that power is drawn from the power source tocharge the battery pack at low-load time periods and to avoid drawingpower from the grid during peak-load hours. The software may be furtherconfigured to manage power output to provide full, fast charging powerin accordance with usage generated by monitoring patterns of usage bythe EV charging system 100. The use of historical information can avoidsituations in which the battery pack becomes fully discharged ordepleted beyond a minimum energy threshold. For example, charging may belimited at a first time based upon a predicted later demand at a secondtime, which later demand may be predicted using historical information.This may spread limited charging capacity more evenly among vehiclethroughout the course of a day or in other situations in which batterypack capacity is expected to be insufficient to fully charge all EVsover a time interval, taking account of the ability to add charge to theenergy storage module 114.

In further embodiments, the system controller 120 executes software(either separately or in coordination with the centralized managementsystem 150) to manage energy draw and use by controlling charging anddischarging over time among multiple EV charging systems 100 at thecharging site 10. Thus, the charge drawn from the power source may belimited or avoided during peak-load hours by charge transfer between theEV charging system 100 and one or more additional EV charging systems100′ and 100″ via the DC bus 101 at the charging site 10, effectivelypooling the energy stored in the batteries of all of the chargingsystems at the charging site 10. As noted above, in some embodiments,the charging site 10 may include one or more external batteries 30connected to the DC bus 101. In such embodiments, the systems controller120 and/or the centralized management system 150 may further manageenergy inflow and outflow at the charging site 10 by controllingselective charging and discharging such batteries at appropriate timeperiods to avoid or reduce total power draw of the charging site 10 fromthe power source during peak-demand or other high-demand times bycharging the batteries of the EV charging systems 100 and the externalbatteries 30 during low-demand times. In some such embodiments, suchenergy management enables the EV charging system 100 to continuecharging vehicles 140 even when the power source is disconnected orunavailable (e.g., when a local power grid is down). As discussedfurther elsewhere herein, the systems controllers 120 of the EV chargingsystems 100 and/or the centralized management system 150 may furthermanage site-wide energy use by controlling charge transfers based upondifferential charge levels or discharge levels associated withdifferential utilization of the various EV charging system 100 at thecharging site 10 in order to effect charge balancing or to ensuresufficient charge availability for charging vehicle 140 at one or moreof the EV charging systems 100.

In some embodiments, the EV charging system 100 may be configured withtwo or more vehicle couplings 132 to enable concurrent charging ofmultiple vehicles 140. The system controller 120 may be configured by auser via the user interface module 122 to support multiple modes ofoperation and may define procedures for charge transfer or powerdistribution that preserve energy levels in the energy storage module114 when multiple vehicles 140 are being concurrently charged. Chargetransfers may be used to transfer power from EV charging systems 100that have available power or are not being used to charge a vehicle 140to EV charging systems 100 that are charging one or more vehicles 140.Distribution of power may be configured to enable fast charging of oneor more vehicles 140 at the expense of other vehicles 140. In thisregard, the vehicle couplings 132 may be prioritized or the systemcontroller 120 may be capable of identifying and prioritizing connectedvehicles 140. In some instances, the system controller 120 may beconfigured to automatically control the respective charge controllers130 to split available power between two vehicles 140 after the secondvehicle 140 is connected. The available power may be evenly splitbetween two vehicles 140 or may be split according to priorities orcapabilities. In some examples, the system controller 120 may conductarbitration or negotiation between connected vehicles 140 to determine asplit of charging capacity. A vehicle 140 may request a charging powerlevel at any given moment based on temperature, battery charge level,and other characteristics of the vehicle 140 and its environment and toachieve maximum charge rate and minimum charging time for the currentcircumstances.

As illustrated, a vehicle 140 may be charged by connecting the vehicle140 to the EV charging system 100 via a vehicle coupling 132. This mayinclude plugging a charging cable of the EV charging system 100 into avehicle charge port 142 of the vehicle 140. The vehicle charge port 142is configured to receive the charging current 116 through the vehiclecoupling 132 and provide such received current to a vehicle powermanagement module 146. The vehicle charge port 142 is further configuredto provide an electronic communication connection between the vehiclecoupling 132 and a vehicle charge controller 144, which controlscharging of the vehicle 140. The vehicle power management module 146 iscontrolled by the vehicle charge controller 144 to provide power to eachof one or more batteries 148 of the vehicle 140 in order to charge suchbattery 148. In some instances, the vehicle charge port 142 includes alocking mechanism to engage and retain a portion of the vehicle coupling132 in place during charging sessions. For example, for safety reasons,the vehicle charge controller 144 may control a locking mechanism of thevehicle charge port 142 to lock a plug of a charging cable in thevehicle charge port 142 while a charging session is active.

FIGS. 2A-B illustrate block diagrams of examples of a charging site 10configured for energy management between multiple EV charging systems200A-D via a local AC circuit 201 or 203. The configurations of thesystems and components shown in FIGS. 2A-B are similar to those shown inFIG. 1A, but the EV charging systems 200A-D are configured and connectedto transfer charge as AC current over a local AC circuit 201 or 203,rather than as DC current over the DC bus 101. Accordingly, each of theEV charging systems 200A-D receives input AC electric power atrespective input ports 102A-D from the electric power grid 20 via thesite meter 22 and a local AC circuit 201. The EV charging systems 200A-Drectify the input AC electric power into DC electric power to chargebatteries of their respective energy storage modules 114A-D, which maythen be used to provide charging currents to vehicles via vehiclecouplings 132A-D (as shown with respect to vehicles 140C and 140D). Thesite meter 22 also provides AC power from the electric power grid 20 tothe non-charging load 24 (e.g., commercial building electricalinfrastructure) at the charging site 10. Operation of each of the EVcharging systems 200A-D is controlled by their respective systemcontrollers 120A-D, which are communicatively connected to thecentralized management system 150, either directly or via the network40, which may include a connection via a local router 42 at the chargingsite 10.

As discussed elsewhere herein, the EV charging systems 200A-D areconfigured and controlled by the system controllers 120A-D and/or thecentralized management system 150 to transfer charge via local ACcircuit 201 or 203 as needed to improve the balance of energy storageand energy demand at each of the EV charging systems 200A-D. To achievesuch energy transfers, the DC power provided by one or more of theenergy storage modules 114A-D is converted to an AC current by aninverter (not shown) and provided to the local AC circuit 201 or 203 inorder to transfer energy to one or more other energy storage modules114A-D. The respective system controllers 120A-D of the donor EVcharging systems 200A-D may be configured to control the phase of the ACoutput power to the local AC circuit 201 or 203 to match that of theinput AC electric power from the site meter 22 or of other donor EVcharging systems 200A-D. As noted above, the input AC electric power maybe received at each of the input ports 102A-D as a 120V or 240Vsingle-phase or three-phase AC power supply. In various embodiments, theAC output power at input ports 102A-D or input ports 204A-D may beprovided according to the same or different voltage and phasecombinations.

FIG. 2A illustrates an embodiment in which one local AC circuit 201carries both the input AC electric power from the electric power grid 20via the site meter 22 and AC charge transferred between the EV chargingsystems 200A-D. In such embodiments, the respective input ports 102A-Dserve to both receive AC current from the local AC circuit 201 andprovide AC current to the local AC circuit 201. In some suchembodiments, the local AC circuit 201 may be further connected to one ormore non-charging loads 24 at the charging site 10 in order to provideAC power to such non-charging loads 24 when the electric power grid 20is disconnected or unavailable.

FIG. 2B illustrates an embodiment in which a separate local AC circuit203 carries AC current for energy transfers among the EV chargingsystems 200A-D, while the local AC circuit 201 carries the input ACelectric power from the electric power grid 20. As illustrated, thelocal AC circuit 201 may be connected to each of the EV charging systems200A-D via respective input ports 102A-D, while the local AC circuit 203may be connected to each of the EV charging systems 200A-D via therespective input ports 204A-D. Such separation of the local AC circuits201 and 203 may be advantageous in some situations by enabling chargetransfers at higher power than the input AC electric power from theelectric power grid 20 or while such input AC electric power is beingreceived from the electric power grid 20. In some embodiments, the localAC circuit 203 is also connected to the site meter 22. In some suchembodiments, the site meter 22 may receive AC power from the local ACcircuit 203 and provide such AC power to one or more non-charging loads24 at the charging site 10 in order to provide AC power to suchnon-charging loads 24 when the electric power grid 20 is disconnected orunavailable.

In some embodiments, the local AC circuit 201 and/or 203 also connectsone or more external battery systems 230 to the EV charging systems200A-D in order to increase the storage capacity at the charging site10. Such external battery systems 230 may receive input AC power fromthe electric power grid 20 via local AC circuit 201 and/or from the EVcharging systems 200A-D via local AC circuit 203 in order to charge oneor more batteries (not shown) of the external battery systems 230. Suchexternal battery systems 230 may include various components (not shown),including controllers and bidirectional inverters or separate rectifiersand inverters in order to convert the input AC power into DC power forstorage and later convert the stored DC power into output AC power forcharge transfers to one or more of the EV charging systems 200A-D.

FIG. 2C illustrates a block diagram of an example of an EV chargingsystem 200 configured in accordance with certain aspects disclosedherein. The EV charging system 200 may be any of the EV charging systems200A-D at the charging site 10 illustrated in FIGS. 2A-B. The componentsand configuration of the EV charging system 200 shown in FIG. 2C aresimilar to those of the EV charging system 100 shown in FIG. 1B, but theEV charging system 200 is configured for transferring charge to anadditional EV charging system 200′ as AC current over a local AC circuit201 or 203 via one or more of the input ports 102 or 104, rather than asDC current over the DC bus 101 via the DC bus connection 160.Accordingly, the power input module 110 of EV charging system 100 isreplaced with a bidirectional inverter 210, which is connected toprovide DC power to the power conversion module 112 and is furtherconnected to receive input AC power from and to provide output AC powerto the input ports 102 and 204. As illustrated, the EV charging system200 also lacks the inverter module 106 and power conditioning module 108to receive input DC electrical energy from DC input port 104 of the EVcharging system 100, but such components may be included in someembodiments of the EV charging system 200. Other components of the EVcharging system 200 are as described above with respect to the EVcharging system 100. Additional or alternative components andfunctionality may be included in further alternative embodiments ofcharging systems.

The bidirectional inverter 210 is configured to alternatively operate inan inverter mode or in a rectifier mode at various times as controlledby the system controller 120. In the rectifier mode, the bidirectionalinverter 210 converts an input AC current from a power source (e.g., theelectric power grid 20 or an additional EV charging system 200′ via alocal AC circuit 201 or 203) into a DC current to provide to the energystorage module 114 via the power conversion module 112. In the invertermode, the bidirectional inverter 210 convers a DC current from theenergy storage module 114 via the power conversion module 112 into anoutput AC current to the local AC circuit 201 or 203 via an input port102 or 204. Thus, when a triggering condition occurs to cause the EVcharging system 200 to provide an AC output power to the local ACcircuit 201 or 203 to transfer charge to an additional EV chargingsystem 200′ at the charging site 10 (e.g., to enable the additional EVcharging system 200′ to charge a vehicle 140′), the bidirectionalinverter operates in the inverter mode to convert a DC current from thepower conversion module 112 into the AC output power and provide such ACoutput power to the local AC circuit 201 or 203 via an input port 102 or204. In some embodiments, a plurality of separate components may insteadbe configured to perform such functionality of the bidirectionalinverter 210, such as by including one or more inverters and rectifiersin the EV charging system 200. In further embodiments, part or all ofthe functionality of the bidirectional inverter 210 may be incorporatedinto the power conversion module 112, or part or all of thefunctionality of the power conversion module 112 may be incorporatedinto the bidirectional inverter 210.

FIG. 3 illustrates a block diagram of an example of a combined EVcharging system 300 configured for both AC and DC charge transfer inaccordance with certain aspects disclosed herein. The EV charging system300 may be any of the EV charging systems 100A-D or EV charging systems200A-D at the charging sites 10 illustrated in FIG. 1A or FIGS. 2A-B.The components and configuration of the EV charging system 300 shown inFIG. 3 combine those of the EV charging system 100 shown in FIG. 1B andthose of the EV charging system 200 shown in FIG. 2C. Thus, the EVcharging system 300 is configured for transferring charge to additionalEV charging system 300′ via a local AC circuit 201 or 203 (e.g., toenable the additional EV charging system 200′ to charge a vehicle 140′)and for transferring charge to additional EV charging systems 300″ and300″′ via DC bus 101 (e.g., to enable the additional EV charging system300″′ to charge a vehicle 140″′). As illustrated, the EV charging system300 includes the bidirectional inverter 210 of EV charging system 200,rather than the power input module 110 of EV charging system 100. Asfurther illustrated, the EV charging system 300 also lacks the invertermodule 106 and power conditioning module 108 to receive input DCelectrical energy from DC input port 104 of the EV charging system 100,but such components may be included in some embodiments of the EVcharging system 300. Other components of the EV charging system 300 areas described above with respect to the EV charging system 100 or EVcharging system 200. Additional or alternative components andfunctionality may be included in further alternative embodiments ofcharging systems.

Additional Description Related to Controllers

FIG. 4 illustrates a block diagram illustrating a simplified example ofa hardware implementation of a controller 400, such as any of the systemcontroller 120, the charge controller 130, the vehicle charge controller144, or the centralized management system 150 disclosed herein. In someembodiments, the controller 400 may be a controller of a site meter 22,an external battery 30, an external battery system 230, or any othercomponent disclosed herein that implements control logic to control anyaspect of the described systems and methods. The controller 400 mayinclude one or more processors 404 that are controlled by somecombination of hardware and software modules. Examples of processors 404include microprocessors, microcontrollers, digital signal processors(DSPs), application-specific integrated circuits (ASICs), fieldprogrammable gate arrays (FPGAs), programmable logic devices (PLDs),state machines, sequencers, gated logic, discrete hardware circuits, andother suitable hardware configured to perform the various functionalitydescribed throughout this disclosure. The one or more processors 404 mayinclude specialized processors that perform specific functions, whichmay be configured by one or more of the software modules 416. The one ormore processors 404 may be configured through a combination of softwaremodules 416 loaded during initialization and may be further configuredby loading or unloading one or more software modules 416 duringoperation.

In the illustrated example, the controller 400 may be implemented with abus architecture, represented generally by the bus 410. The bus 410 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the controller 400 and the overall designconstraints. The bus 410 links together various circuits including theone or more processors 404 and storage 406. Storage 406 may includememory devices and mass storage devices, any of which may be referred toherein as computer-readable media. The bus 410 may also link variousother circuits, such as timing sources, timers, peripherals, voltageregulators, and power management circuits. A bus interface 408 mayprovide an interface between the bus 410 and one or more line interfacecircuits 412, which may include a line interface transceiver circuit 412a and a radio frequency (RF) transceiver circuit 412 b. A line interfacetransceiver circuit 412 a may be provided for each networking technologysupported by the controller. In some instances, multiple networkingtechnologies may share some or all of the circuitry or processingmodules found in a line interface circuit 412, such as line interfacetransceiver circuit 412 a for wired communication and RF transceivercircuit 412 b for wireless communication. Each line interface circuit412 provides a means for communicating with various other devices over atransmission medium. In some embodiments, a user interface 418 (e.g.,touchscreen display, keypad, speaker, or microphone) may also beprovided, and may be communicatively coupled to the bus 410 directly orthrough the bus interface 408.

A processor 404 may be responsible for managing the bus 410 and forgeneral processing that may include the execution of software stored ina computer-readable medium that may include the storage 406. In thisrespect, the processor 404 of the controller 400 may be used toimplement any of the methods, functions, and techniques disclosedherein. The storage 406 may be used for storing data that is manipulatedby the processor 404 when executing software, and the software may beconfigured to implement any of the methods disclosed herein.

One or more processors 404 in the controller 400 may execute software.Software may include instructions, instruction sets, code, codesegments, program code, programs, subprograms, software modules,applications, software applications, software packages, routines,subroutines, objects, executables, threads of execution, procedures,functions, algorithms, etc., whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise. Thesoftware may reside in computer-readable form in the storage 406 or inan external computer readable medium. The external computer-readablemedium and/or storage 406 may include a non-transitory computer-readablemedium. A non-transitory computer-readable medium includes, by way ofexample, a magnetic storage device (e.g., hard disk, floppy disk,magnetic strip), an optical disk, a smart card, a flash memory device(e.g., a “flash drive,” a card, a stick, or a key drive), a randomaccess memory (RAM), a read only memory (ROM), a programmable ROM(PROM), an erasable PROM (EPROM), an electrically erasable PROM(EEPROM), a register, a removable disk, and any other suitable mediumfor storing software and/or instructions that may be accessed and readby a computer. Portions of the computer-readable medium or the storage406 may reside in the controller 400 or external to the controller 400.The computer-readable medium and/or storage 406 may be embodied in acomputer program product. By way of example, a computer program productmay include a computer-readable medium in packaging materials. Thoseskilled in the art will recognize how best to implement the describedfunctionality presented throughout this disclosure depending on theparticular application and the overall design constraints imposed on theoverall system.

The storage 406 may maintain software maintained or organized inloadable code segments, modules, applications, programs, etc., which maybe referred to herein as software modules 416. Each of the softwaremodules 416 may include instructions and data that, when installed orloaded on the controller 400 and executed by the one or more processors404, contribute to a run-time image 414 that controls the operation ofthe one or more processors 404. When executed, certain instructions maycause the controller 400 to perform functions in accordance with certainmethods, algorithms, and processes described herein.

Some of the software modules 416 may be loaded during initialization ofthe controller 400, and these software modules 416 may configure thecontroller 400 to enable performance of the various functions disclosedherein. For example, some software modules 416 may configure internaldevices or logic circuits 422 of the processor 404, and may manageaccess to external devices such as line interface circuits 412, the businterface 408, the user interface 418, timers, mathematicalcoprocessors, etc. The software modules 416 may include a controlprogram or an operating system that interacts with interrupt handlersand device drivers to control access to various resources provided bythe controller 400. The resources may include memory, processing time,access to the line interface circuits 412, the user interface 418, etc.

One or more processors 404 of the controller 400 may be multifunctional,whereby some of the software modules 416 are loaded and configured toperform different functions or different instances of the same function.For example, the one or more processors 404 may additionally be adaptedto manage background tasks initiated in response to inputs from the userinterface 418, the line interface circuits 412, and device drivers. Tosupport the performance of multiple functions, the one or moreprocessors 404 may be configured to provide a multitasking environment,whereby each of a plurality of functions is implemented as a set oftasks serviced by the one or more processors 404 as needed or desired.In one example, the multitasking environment may be implemented using atimesharing program 420 that passes control of a processor 404 betweendifferent tasks, whereby each task returns control of the one or moreprocessors 404 to the timesharing program 420 upon completion of anyoutstanding operations or in response to an input such as an interrupt.When a task has control of the one or more processors 404, theprocessing circuit is effectively specialized for the purposes addressedby the function associated with the controlling task. The timesharingprogram 420 may include an operating system, a main loop that transferscontrol on a round-robin basis, a function that allocates control of theone or more processors 404 in accordance with a prioritization of thefunctions, or an interrupt-driven main loop that responds to externalevents by providing control of the one or more processors 404 to ahandling function.

Exemplary Methods for Energy Management at a Charging Site

FIG. 5 illustrates a flow diagram of an example energy management method500 for monitoring a charging site 10 and controlling charge transfersbetween multiple EV charging systems in accordance with certain aspectsdisclosed herein. The charging site 10 may include any combination ofone or more of the DC bus 101, the local AC circuit 201, or the local ACcircuit 203 as described above. In various embodiments, all of the EVcharging systems at the charging site are EV charging systems 100 or areEV charging systems 200. In alternative embodiments, one or more EVcharging systems 300 may be connected with either or both one or more EVcharging systems 100 or one or more EV charging systems 200 at thecharging site 10. The exemplary method 500 may be implemented by one ormore system controllers 120 of corresponding EV charging systems and/ora centralized management system 150 in order to determine and effectcharge transfers among the EV charging systems.

The example energy management method 500 begins with charging theplurality of EV charging systems at the charging site 10 from a powersource of the charging site 10 in order to store energy at each of theplurality of EV charging systems (block 502). In some embodiments, powersource data regarding the availability or other information about thepower source may be received (block 504). Operating data regarding theoperating status or parameters of each of the plurality of EV chargingsystems is also obtained (block 506). Based upon the operating dataand/or power source data, it is determined whether a triggeringcondition for a charge transfer has occurred (block 508). When such atriggering condition has not occurred (block 510) and the power sourceis available (block 512), the EV charging systems continue to charge(block 502). When such a triggering condition has not occurred (block510) but the power source is not available (block 512), the power sourcedata and operating data continues to be monitored (block 504 and 506).When such triggering condition has occurred (block 510), a chargetransfer plan is determined (block 514), and one or more of the EVcharging systems and/or external battery systems are controlled toeffect the charge transfer (block 516). Operating data is monitored(block 518) while the charge transfer is ongoing (block 520). When thecharge transfer is complete or otherwise discontinued (block 520), theEV charging systems continue charging from the power source (block 502)if the power source is available (block 512), or the power source dataand operating data continues to be monitored (block 504 and 506) if thepower source is unavailable (block 512). Additional or alternativeaspects may be included in some embodiments.

At block 502, the centralized management system 150 and/or one or moresystem controllers 120 associated with the EV charging systems controlthe EV charging systems to charge from the power source of the chargingsite 10 (e.g., the electric power grid 20). In some embodiments, thepower source provides an AC or DC input electric power at a lowervoltage or lower wattage than the output charging current used to chargevehicles (e.g., vehicles 140). Therefore, charging the batteries of theEV charging systems may occur slowly over a substantially longer timethan discharging occurs. In embodiments in which the charging site 10includes one or more external batteries 30 or external battery systems230, the batteries of such components may also be charged from eitherthe power source of the charging site 10 or from an AC or DC output fromone or more of the EV charging systems.

At block 504, in some embodiments, the centralized management system 150and/or one or more system controllers 120 associated with the EVcharging systems obtain power source data regarding the power source.Such power source data may include an indication of whether the powersource is available (e.g., whether the electric power grid 20 isconnected and powered to provide electric power to the charging site10). Such power source data may further include demand data regardingload on or demand charges for the power source. In some embodiments, thepower source data may further include predictions of future availabilityor demand, as well as current availability or demand. For on-site powersources such as solar or wind power generators, predictions of futureavailability may include predicting future environmental conditions andoutput levels. Thus, the power source data may include one or more ofthe following charging site conditions: current availability of inputelectric power from the power source, predicted future availability ofinput electric power from the power source, current demand for electricpower from the power source, or predicted future demand for electricpower from the power source. In various embodiments, the power sourcedata may be received by an electronic message from the site meter 22, aserver or controller associated with the power source, or monitoringcomponents (e.g., sensors) disposed at the charging site 10 or at aninterconnect of the power source near the charging site 10.

At block 506, the centralized management system 150 and/or one or moresystem controllers 120 associated with the EV charging systems obtainoperating data for the plurality of EV charging systems at the chargingsite 10. Such operating data may include data regarding an operationalstatus of each EV charging system (e.g., whether operating normally, inneed of repair, charging, discharging, or at full charge), a chargelevel of the one or more batteries of each EV charging system, acharging rate of each EV charging system regarding charging from thepower source, a discharging rate of each EV charging system relating tovehicle charging, or an energy transfer rate of each EV charging systemrelating to energy transfers among the EV charging systems. Thecharging, discharging, and energy transfer rates may include currentrates or potential rates (e.g., maximum available rates). In embodimentsin which the charging site 10 includes one or more external batteries 30or external battery systems 230, corresponding operating data for suchcomponents may also be obtained. The operating data may be obtained byreceiving (either directly or indirectly) electronic messages from therespective system controllers 120 the EV charging systems, by receiving(either directly or indirectly) electronic messages from the centralizedmanagement system 150, by detecting current operating conditions of anEV charging system from sensors disposed within the EV charging system,by accessing operating data stored in a local or remote database, or bygenerating predictions of future operating data based upon currentoperating data or stored past operating data. For example, each of theEV charging systems may send electronic messages containing operatingdata regarding their own current operating conditions to the centralizedmanagement system 150 or to each other EV charging system at thecharging site 10.

At block 508, the centralized management system 150 and/or one or moresystem controllers 120 associated with the EV charging systems determinewhether a triggering condition for a charge transfer via one or more ofthe DC bus 101, the local AC circuit 201, or the local AC circuit 203has occurred. Such determination of occurrence of a triggering conditionmay be determined based upon the operating data and/or the power sourcedata by a system controller 120 or by the centralized management system150. In some embodiments, the centralized management system 150determines occurrence of a triggering condition for a charge transfer atthe charging site 10, then sends a command to one or more of the EVcharging systems in an electronic message to cause the one or more EVcharging systems to effect the charge transfer. For such one or more EVcharging systems, determination of occurrence of the triggeringcondition may comprise detecting receipt of such command from thecentralized management system 150. In further embodiments, the systemcontrollers 120 of the EV charging systems may determine occurrence ofthe triggering condition based upon their own operating data and/oroperating data from the system controllers 120 of the other EV chargingsystems at the charging site 10. In some such embodiments, the systemcontrollers 120 may exchange operating data with other systemcontrollers 120 of the EV charging systems at the charging site 10 tofacilitate determination of the triggering condition by all the systemcontrollers 120 at the charging site 10. In further such embodiments,the system controllers 120 may instead determine triggering conditionsbased upon the operating data of their own respective EV chargingsystems (and, in some such embodiments, base upon the power source data)in order to generate and transmit charge transfer requests to the othersystem controllers 120 of the EV charging systems at the charging site10 (either directly or via the centralized management system 150).

In some embodiments, occurrence of the triggering condition may includedetection of disconnection of the power source from the EV chargingsystems (e.g., disconnection of the electric power grid 20 from thelocal AC circuit 201). Detecting disconnection of the power source mayinclude detecting receipt of an electronic message indication suchdisconnection from the site meter 22 or from the centralized managementsystem 150. Alternatively, detecting disconnection of the power sourcemay include detecting an absence of input electric power at the inputports 102 and/or 104 of one or more of the EV charging systems. Infurther embodiments, determining occurrence of the triggering conditionmay include determining a demand level for the power source exceeds athreshold demand level (e.g., determining the load or demand charges ofthe electric power grid 20 exceeding thresholds associated with highdemand relative to supply of power to the grid). An indication of suchdemand level or an indication that the demand level exceeds to thethreshold demand level may be received from the site meter 22, from aserver or controller associated with the power source, or from thecentralized management system 150.

Occurrence of the triggering condition for the charge transfer thusincludes occurrence of one or more conditions relating to the powersource, the EV charging systems, and/or any external batteries 30 orexternal battery systems 230. As discussed further below with respect tothe example charge balancing method 600 illustrated in FIG. 6 , in someembodiments, the triggering condition may comprise a determination ofcharge imbalance between batteries of the EV charging systems exceedinga threshold charge differential or of a discharge imbalance betweencharging currents output by the EV charging systems exceeding athreshold discharge differential.

In some embodiments, the triggering condition may be associated with oneor more external batteries 30 or external battery systems 230 at thecharging site 10, which triggering condition may be a differenttriggering condition employing a separate set of thresholds or rules fordetermining when to transfer charge to or from the one or more externalbatteries 30 or external battery systems 230. For example, thetriggering conditions for transferring charge to the one or moreexternal batteries 30 or external battery systems 230 may comprisedetermining sufficient availability of the power source or a sufficientcharge at one or more of the EV charging systems (which may bedetermined by a higher threshold than that used for inter-chargertransfers between EV charging systems), thus indicating sufficient powerat the EV charging systems to cause storage of additional power at theone or more external batteries 30 or external battery systems 230.Similarly, the triggering conditions for transferring charge from theone or more external batteries 30 or external battery systems 230 to oneor more EV charging systems may be determined using lower thresholds forsuch charge transfers because the external batteries 30 or externalbattery systems 230 cannot directly provide charging current to chargevehicles 140. Since the one or more external batteries 30 or externalbattery systems 230 are disposed at the charging site 10 to providepower to the EV charging systems, it may be unnecessary to reserve powerin the one or more external batteries 30 or external battery systems230, while it may be desirable to maintain a minimum reserve power ineach of the EV charging systems in some situations.

At block 510, when no triggering condition for a charge transfer hasoccurred, the example energy management method 500 continues at block512. At block 512, the centralized management system 150 and/or one ormore system controllers 120 associated with the EV charging systemsdetermine whether the power source is available for charging the EVcharging systems and any external batteries 30 or external batterysystems 230 at the charging site 10 based upon the power source data. Ifthe power source is determined to be available or if no power sourcedata is available, the example energy management method 500 continueswith charging or attempting to charge the EV charging systems using thepower source at block 502. If the power source is determined not to beavailable based upon the power source data, the example energymanagement method 500 continues with obtaining power source data atblock 504 and operating data at block 506. In some embodiments,determining the power source is not available may include determiningthat the power source is disconnected from the EV charging systems(e.g., by disconnection of the electric power grid 20 at the site meter22 to avoid peak-demand charges). In further embodiments, determiningthe power source is not available may include determining that a demandlevel for electric power from the power source exceeds a thresholddemand level (e.g., by receiving an indication of power source load ordemand charges exceeding thresholds). In some such embodiments, thethreshold demand level may be dynamically determined based upon chargelevels and vehicle charging demand at the plurality of EV chargingsystems.

At block 510, when a triggering condition for a charge transfer hasoccurred, the example energy management method 500 continues at block514. At block 514, the centralized management system 150 and/or one ormore system controllers 120 associated with the EV charging systemsdetermine a charge transfer plan for transferring charge to or from atleast one EV charging system via one or more of the DC bus 101, thelocal AC circuit 201, or the local AC circuit 203. The charge transferplan defines the parameters of the charge transfer, includingidentifying each donor EV charging system and each recipient EV chargingsystem and the timing and extent of the charge to be transferred. Thecharge transfer plan may include transferring charge as an AC or DCcurrent between EV charging systems at the charging site 10. In someembodiments, the charge transfer plan may include transferring DCcurrent to or from one or more external batteries 30 via the DC bus 101.In further embodiments, the charge transfer plan may includetransferring AC current to or from one or more external battery systems230 via the local AC circuit 201 or 203. In some embodiments, the chargetransfer plan may be determined by the system controllers 120 of the oneor more EV charging systems that will donate or receive a charge toeffect the charge transfer, which may include coordination throughsending electronic messages between the system controllers 120 to definethe parameters of the charge transfer.

At block 516, the centralized management system 150 and/or one or moresystem controllers 120 associated with the EV charging systems cause theone or more EV charging systems and any external batteries 30 orexternal battery systems 230 to transfer the charge according to theparameters of the charge transfer plan in order to effect the chargetransfer. In some embodiments, the centralized management system 150sends an electronic message to the system controller 120 of each donorEV charging system and each recipient EV charging system to cause therespective system controllers 120 to control the EV charging systems toeffect the charge transfer. In further embodiments, the centralizedmanagement system 150 sends an additional electronic message to eachexternal battery system 230 involved in the charge transfer plan toeffect the charge transfer. To effect the charge transfer, the systemcontroller 120 of each donor EV charging system controls the such EVcharging system to either (i) provide a DC output power from its one ormore batteries (e.g., the energy storage module 114) to the DC busconnection 160 in order to provide the DC output power to the DC bus 101or (ii) provide a DC output power from its one or more batteries (e.g.,the energy storage module 114) to the bidirectional inverter 210 andconvert the DC output to an AC output power to provide the AC outputpower to the local AC circuit 201 or 203 via an input port 102 or 204.Correspondingly, to effect the charge transfer, the system controller120 of each recipient EV charging system controls the such EV chargingsystem to either (i) receive and charge its one or more batteries (e.g.,the energy storage module 114) with a DC input power from the DC bus 101via the DC bus connection 160 or (ii) receive an AC input power from thelocal AC circuit 201 or 203 via an input power 102 or 204 and convertthe AC input power by the bidirectional inverter 210 into a DC inputpower to charge its one or more batteries (e.g., the energy storagemodule 114). In embodiments in which the charge transfer plan includesone or more external batteries 30 or external battery systems 230, acontroller associated with each such external battery 30 or externalbattery system 230 may control one or more batteries thereof to eitherprovide or receive DC power to or from the DC bus 101 or AC power to orfrom the local AC circuit 201 or 203 to effect the charge transfer.

At block 518, the centralized management system 150 and/or one or moresystem controllers 120 associated with the EV charging systems monitoroperating data relating to the EV charging systems at the charging site10 during the charge transfer. At block 520, the centralized managementsystem 150 and/or one or more system controllers 120 associated with theEV charging systems determine whether to continue the charge transferaccording to the charge transfer plan based upon the current operatingdata. In some embodiments, the charge transfer plan may be discontinuedor adjusted based upon changes in the operating data (e.g., increasedavailability of or reduced demand on the power source, arrival of avehicle 140 for charging at a donor EV charging station, or departure ofa vehicle 140 after charging at a recipient EV charging station). Whenit is determined at block 520 to continue the charge transfer, theexample energy management method 500 continues to monitor the operatingdata at block 518. When it is determined at block 520 not to continuethe charge transfer, the example energy management method 500 continuesby determining whether the power source is available at block 512. Ifthe power source is determined to be available or if no power sourcedata is available, the example energy management method 500 continueswith charging or attempting to charge the EV charging systems using thepower source at block 502. If the power source is determined not to beavailable based upon the power source data, the example energymanagement method 500 continues with obtaining power source data atblock 504 and operating data at block 506. The example energy managementmethod 500 continues while the charging site 10 is operational.

FIG. 6 illustrates a flow diagram of an example charge balancing method600 for determining charge imbalance and charge transfers betweenmultiple EV charging systems at a charging site 10 to implement certainaspects of the example energy management method 500 in accordance withcertain aspects disclosed herein. The exemplary method 600 may berepeatedly implemented by one or more system controllers 120 ofcorresponding vehicle chargers and/or a centralized management system150 in order to monitor the charging site 10 and to determine chargetransfers among the EV charging systems in order to perform a portion ofthe example energy management method 500. As with the example energymanagement method 500, the charging site 10 may include any combinationof one or more of the DC bus 101, the local AC circuit 201, or the localAC circuit 203 as described above. In various embodiments, all of the EVcharging systems at the charging site are EV charging systems 100 or areEV charging systems 200. In alternative embodiments, one or more EVcharging systems 300 may be connected with either or both one or more EVcharging systems 100 or one or more EV charging systems 200 at thecharging site 10.

The example charge balancing method 600 begins with monitoring operatingdata for the plurality of EV charging systems at the charging site 10(block 602), then determining charge levels of batteries of the EVcharging systems (block 604) and discharge levels of the batteries ofthe EV charging systems (block 606) from the operating data. In someembodiments, availability of the power supply for the charging site 10may be determined (block 608). Based upon these determinations, one ormore charge imbalances or discharge imbalances of the batteries of theEV charging systems are determined (block 610). If a triggeringcondition is determined to have occurred based upon such power supplyavailability and the determined charge and/or discharge imbalances(block 612), one or more donor batteries and recipient batteries for acharge transfer are selected (block 614). A charge transfer plan betweenthe donor batteries and the recipient batteries is then generated (block616). When the charge transfer plan has been implemented (block 618) orif no such triggering condition is determined to have occurred (block612), the example charge balancing method 600 ends. Additional oralternative aspects may be included in some embodiments.

At block 602, the centralized management system 150 and/or one or moresystem controllers 120 associated with the EV charging systems obtainand monitor operating data for each of the plurality of EV chargingsystems at the charging site 10. In some embodiments, this may includesystem controllers 120 of the EV charging systems sending the operatingdata in electronic messages to the centralized management system 150 viathe network 40, which may occur periodically, upon a change to theoperating data, or upon receipt of a request for such operating datafrom the centralized management system 150. In embodiments in which thecharging site 10 includes one or more external batteries 30 or externalbattery systems 230, corresponding operating data for such componentsmay also be monitored.

At block 604, the centralized management system 150 and/or one or moresystem controllers 120 associated with the EV charging systems determinecharge levels of batteries (e.g., energy storage modules 114) of the EVcharging systems and any external batteries 30 or external batterysystems 230 at the charging site 10. In some embodiments, the chargelevels of the batteries may be determined directly as being included inthe operating data. In further embodiments, the charge levels may becalculated from current flowing into and out of the batteries over time.

At block 606, the centralized management system 150 and/or one or moresystem controllers 120 associated with the EV charging systems determinedischarge levels of the batteries of the EV charging systems at thecharging site 10. The discharge levels of the batteries of the EVcharging systems may be determined as a total power of the chargingcurrent provided by each of the EV charging stations to charge vehicles140 over one or more time intervals. For example, the discharge levelsmay be determined for each EV charging system for both a current timeinterval (e.g., a current day), as well as a historical time interval(e.g., over the past month). Using both current and historical timeintervals may be useful in predicting likely vehicle charging demand foreach of the EV charging systems for a relevant future time interval(e.g., a remainder of the day).

At block 608, in some embodiments, the centralized management system 150and/or one or more system controllers 120 associated with the EVcharging systems determine power supply availability (e.g., whether theelectric power grid 20 is connected to the EV charging systems andpowered). Power source availability may be determined based upon powersource data obtained from the site meter 22, a server or controllerassociated with the power source, or monitoring components (e.g.,sensors) disposed at the charging site 10 or at an interconnect of thepower source near the charging site 10. In some embodiments, determiningpower supply availability may include determining current availabilityand predicting future availability of the power source. In furtherembodiments, determining power supply availability may includedetermining a demand level for the power source, such as an indicationof load on or demand charges for the power source.

At block 610, the centralized management system 150 and/or one or moresystem controllers 120 associated with the EV charging systems determinecharge imbalances and/or discharge imbalanced between the EV chargingsystems at the charging site 10. The charge balances and dischargeimbalances may be determined between each pair of EV charging stationsat the charging site 10 in order to identify charge transfer candidatesamong the EV charging stations. The charge imbalances may be determinedas a charge differential between the stored charge levels of the energystorage modules 114 of each of the EV charging systems. Likewise, thedischarge imbalances may be determined as a discharge differentialbetween the charging current provided to charge vehicles 140 over apredetermined time interval by each of the EV charging systems.

At block 612, the centralized management system 150 and/or one or moresystem controllers 120 associated with the EV charging systems determinewhether a triggering condition has occurred. The triggering conditionmay be determined based upon one or more of the charge levels, thedischarge levels, the charge or discharge imbalances, or the powersupply availability. In some embodiments, occurrence of the triggeringcondition may be determined based upon a charge imbalance exceeding athreshold charge differential. In further embodiments, occurrence of thetriggering condition may be determined based upon a discharge imbalanceexceeding a threshold discharge differential. In still furtherembodiments, occurrence of the triggering condition may be based upon aweighted score combining charge differentials and dischargedifferentials exceeding a threshold score. In some embodiments, any ofthe threshold charge differential, the threshold discharge differential,or the threshold score may be dynamically determined based upon one ormore of the following charging site conditions: current availability ofinput electric power from the power source, predicted futureavailability of input electric power from the power source, currentcharging demand for each of the EV charging systems, predicted futuredemand for each of the EV charging systems, or operational statuses ofthe EV charging systems. In further embodiments, occurrence of thetriggering condition may be based at least in part upon a current orpredicted future availability or demand level of the power source. Thus,the triggering condition may include disconnection of the power sourcefrom the EV charging systems, which may be indicated by the power sourcedata. Similarly, the triggering condition may include determination thata demand level of the power source exceeds a threshold demand level(e.g., determining the load or demand charges of the electric power grid20 exceeding thresholds associated with high demand relative to supplyof power to the grid). When a triggering condition has occurred, theexample charge balancing method 600 continues at block 614. Otherwise,when no triggering condition has occurred, the example charge balancingmethod 600 ends.

At block 614, the centralized management system 150 and/or one or moresystem controllers 120 associated with the EV charging systems selectone or more charge donor batteries and one or more charge recipientbatteries from the EV charging systems and any external batteries 30 orexternal battery systems 230 at the charging site 10. The donorbatteries may be selected as batteries having the highest current chargelevels, the lowest current or predicted discharge levels, or thegreatest differential between current charge levels and expecteddischarge levels. Batteries of any external batteries 30 or externalbattery systems 230 may be preferentially selected as donor batteries insome embodiments. The recipient batteries may be selected as batterieshaving the lowest current charge levels, the highest current orpredicted discharge levels, or the greatest differential betweenexpected discharge levels and current charge levels.

At block 616, the centralized management system 150 and/or one or moresystem controllers 120 associated with the EV charging systems generatea charge transfer plan between the donor batteries and recipientbatteries for a charge transfer via one or more of the DC bus 101, thelocal AC circuit 201, or the local AC circuit 203. The charge transferplan may include parameters defining the extent of the charge transferand timing of the charge transfer. For example, the charge transfer planmay include parameters specifying a maximum charge to transfer, amaximum instantaneous AC or DC current of the charge transfer, and amaximum duration of the charge transfer. In some embodiments, the chargetransfer plan may include multiple stages in order to smooth the energytransfer at the donor or recipient EV charging systems. For example,during an initial stage, the energy transferred may be graduallyincreased over an initial time interval in order to avoid excessivefluctuations of input power received by a recipient EV charging system.Similarly, during a final stage, the energy transferred may be graduallydecreased over a final time interval to again avoid excessivefluctuations of input power received by a recipient EV charging system.Specifying the duration of such stages may enable the recipient EVcharging station to adjust its power draw from the power source or powerprovision from its one or more batteries.

At block 618, the centralized management system 150 and/or one or moresystem controllers 120 associated with the EV charging systemsimplements the charge transfer plan to cause the EV charging systems toeffect the charge transfer. In some embodiments, the centralizedmanagement system 150 sends an electronic message to the systemcontroller 120 of each donor EV charging system and each recipient EVcharging system to cause the respective system controllers 120 tocontrol the EV charging systems to implement the charge transfer plan toeffect the charge transfer. In embodiments in which the charge transferplan includes batteries of one or more external batteries 30 or externalbattery systems 230, the centralized management system 150 and/or one ormore system controllers 120 may send commands to controllers of the oneor more external batteries 30 or external battery systems 230 to controlthe charging or discharging of such external batteries 30 or externalbattery systems 230. When the charge transfer plan has been implemented,the example charge balancing method 600 ends.

Other Considerations

Although the preceding text sets forth a detailed description ofnumerous different embodiments, it should be understood that the legalscope of the invention is defined by the words of the claims set forthat the end of this patent. The detailed description is to be construedas exemplary only and does not describe every possible embodiment, asdescribing every possible embodiment would be impractical, if notimpossible. One could implement numerous alternate embodiments, usingeither current technology or technology developed after the filing dateof this patent, which would still fall within the scope of the claims.

It should also be understood that, unless a term is expressly defined inthis patent using the sentence “As used herein, the term ‘______’ ishereby defined to mean . . . ” or a similar sentence, there is no intentto limit the meaning of that term, either expressly or by implication,beyond its plain or ordinary meaning, and such term should not beinterpreted to be limited in scope based upon any statement made in anysection of this patent (other than the language of the claims). To theextent that any term recited in the claims at the end of this patent isreferred to in this patent in a manner consistent with a single meaning,that is done for sake of clarity only so as to not confuse the reader,and it is not intended that such claim term be limited, by implicationor otherwise, to that single meaning. No claim element is to beconstrued as a means plus function unless the element is expresslyrecited using the phrase “means for.”

Throughout this specification, plural instances may implementcomponents, operations, or structures described as a single instance.Although individual operations of one or more methods are illustratedand described as separate operations, one or more of the individualoperations may be performed concurrently, and nothing requires that theoperations be performed in the order illustrated. Structures andfunctionality presented as separate components in example configurationsmay be implemented as a combined structure or component. Similarly,structures and functionality presented as a single component may beimplemented as separate components. These and other variations,modifications, additions, and improvements fall within the scope of thesubject matter herein. Unless specifically stated otherwise, the term“some” refers to one or more. Likewise, use of the “a” or “an” areemployed to describe elements and components of the embodiments herein.This is done merely for convenience and to give a general sense of thedescription. This description, and the claims that follow, should beread to include one or at least one and the singular also includes theplural unless the context clearly indicates otherwise.

Upon reading this disclosure, those of skill in the art will appreciatestill additional alternative structural and functional designs for thesystems and a methods disclosed herein. Thus, while particularembodiments and applications have been illustrated and described, it isto be understood that the disclosed embodiments are not limited to theprecise construction and components disclosed herein. Variousmodifications, changes and variations, which will be apparent to thoseskilled in the art, may be made in the arrangement, operation anddetails of the method and apparatus disclosed herein without departingfrom the spirit and scope defined in the appended claims.

What is claimed is:
 1. A vehicle charging system for charging a vehicle, comprising: a power input port configured to receive input electric power from a power source; a battery configured to receive and store electric power derived from the input electric power received at the power input port; a vehicle coupling configured to receive a charging current from the battery and to provide an electrical interconnect between the vehicle charging system and the vehicle in order to provide the charging current to the vehicle; an inter-charger connection communicatively connected to the battery and configured to provide a direct current (DC) output to an additional vehicle charging system and to receive a DC input from the additional vehicle charging system via a direct connection with the additional vehicle charging system, wherein the direct connection is a DC bus and wherein the inter-charger connection is further configured to provide the DC output to an external battery connected to the DC bus and to receive the DC input from the external battery; and a system controller comprising one or more processors configured to: determine occurrence of a triggering condition for charge transfer between the battery of the vehicle charging system and an additional battery of the additional vehicle charging system via the direct connection; in response to determining occurrence of the triggering condition, control the vehicle charging system to effect the charge transfer based upon the triggering condition by either (i) providing the DC output from the battery to the additional vehicle charging system via the inter-charger connection or (ii) receiving and charging the battery with the DC input from the additional charging system via the inter-charger connection; determine occurrence of a second triggering condition for additional charge transfer between the battery of the vehicle charging system and the external battery via the DC bus; and in response to determining occurrence of the second triggering condition, control the vehicle charging system to effect the additional charge transfer based upon the second triggering condition by either (i) providing the DC output from the battery to the external battery via the inter-charger connection or (ii) receiving and charging the battery with the DC input from the external battery via the inter-charger connection.
 2. The vehicle charging system of claim 1, wherein: the DC bus connects a plurality of vehicle charging systems at a vehicle charging site, including the vehicle charging system and the additional vehicle charging system; and the inter-charger connection is a DC bus connection.
 3. The vehicle charging system of claim 1, further comprising: a power conversion circuit configured to convert the input electric power into an energy storage current used to charge the battery.
 4. The vehicle charging system of claim 3, wherein the input electric power is an alternating current (AC) input electric power and the energy storage current is a DC energy storage current.
 5. The vehicle charging system of claim 3, wherein: the power conversion circuit is further configured to receive a DC current from the battery and provide the charging current to the vehicle coupling using the DC current; and the power conversion circuit is further configured to connect the battery to the inter-charger connection.
 6. The vehicle charging system of claim 1, wherein the triggering condition comprises receiving a command from a centralized management system communicatively connected to the vehicle charging system and the additional vehicle charging system via a communication network.
 7. The vehicle charging system of claim 1, wherein the system controller determines occurrence of the triggering condition based at least in part upon a charge level of the battery and an additional charge level of the additional battery of the additional charging system, wherein the additional charge level is received in an electronic message received from the additional charging system.
 8. The vehicle charging system of claim 1, wherein the system controller determines occurrence of the triggering condition based at least in part upon a charge imbalance between a charge level of the battery of the vehicle charging system and an additional charge level of the additional battery of the additional charging system exceeding a threshold charge differential.
 9. The vehicle charging system of claim 8, wherein the system controller determines the threshold charge differential dynamically based upon one or more of the following charging site conditions: current availability of the input electric power from the power source, predicted future availability of the input electric power from the power source, current charging demand for each of the vehicle charging system and the additional vehicle charging system, predicted future demand for each of the vehicle charging system and the additional vehicle charging system, or operational statuses of the vehicle charging system and the additional vehicle charging system.
 10. The vehicle charging system of claim 1, wherein the triggering condition comprises a discharge imbalance between the charging current provided by the vehicle coupling of the vehicle charging system and an additional charging current of an additional vehicle coupling of the additional charging system exceeding a threshold discharge differential over a predetermined time interval.
 11. A method for managing energy transfers between a plurality of vehicle charging systems each configured to charge vehicles at a charging site, comprising: charging, via respective power input ports, a battery of a vehicle charging system and an additional battery of an additional vehicle charging system at the charging site using an input electric power from a power source; determining, by a system controller of the vehicle charging system, occurrence of a triggering condition for charge transfer between the battery of the vehicle charging system and the additional battery of the additional vehicle charging system via a direct connection between the vehicle charging system and the additional vehicle charging system, wherein the direct connection is a DC bus; in response to determining occurrence of the triggering condition, controlling, by the system controller, the vehicle charging system to effect the charge transfer based upon the triggering condition by either (i) providing a direct current (DC) output from the battery to the additional vehicle charging system via an inter-charger connection of the vehicle charging system or (ii) receiving and charging the battery with a DC input from the additional charging system via the inter-charger connection, wherein the inter-charger connection is communicatively connected to the battery and configured to provide the DC output to the addition vehicle charging system and to receive the DC input from the additional vehicle charging system via the direct connection with the additional vehicle charging system; determining, by the system controller, occurrence of a second triggering condition for additional charge transfer between the battery of the vehicle charging system and an external battery connected to the inter-charger connection via the DC bus; and in response to determining occurrence of the second triggering condition, controlling, by the system controller, the vehicle charging system to effect the additional charge transfer based upon the second triggering condition by either (i) providing the DC output from the battery to the external battery via the inter-charger connection or (ii) receiving and charging the battery with the DC input from the external battery via the inter-charger connection.
 12. The method of claim 11, wherein: the DC bus connects the plurality of vehicle charging systems at a vehicle charging site, including the vehicle charging system and the additional vehicle charging system; and the inter-charger connection is a DC bus connection.
 13. The method of claim 11, wherein the triggering condition comprises receiving a command from a centralized management system communicatively connected to the vehicle charging system and the additional vehicle charging system via a communication network, and further comprising: sending, to the centralized management system via the communication network, operating data from each of the vehicle charging system and the additional vehicle charging system; and receiving, at the system controller via the communication network, the command from the centralized management system to effect the charge transfer.
 14. The method of claim 13, further comprising: receiving, at an additional system controller of the additional vehicle charging system via the communication network, an additional command from the centralized management system to effect the charge transfer.
 15. The method of claim 11, wherein determining occurrence of the triggering condition comprises: determining, by the system controller, a charge level of the battery of the vehicle charging system; receiving, at the system controller, an electronic message from the additional charging system, wherein the electronic message includes an indication of an additional charge level of the additional battery of the additional charging system; determining, by the system controller, occurrence of the triggering condition based at least in part upon a charge imbalance between the charge level and the additional charge level exceeding a threshold charge differential.
 16. The method of claim 15, wherein the system controller determines the threshold charge differential dynamically based upon one or more of the following charging site conditions: current availability of the input electric power from the power source, predicted future availability of the input electric power from the power source, current charging demand for each of the vehicle charging system and the additional vehicle charging system, predicted future demand for each of the vehicle charging system and the additional vehicle charging system, or operational statuses of the vehicle charging system and the additional vehicle charging system.
 17. The method of claim 11, wherein the triggering condition comprises a discharge imbalance between a charging current provided by a vehicle coupling of the vehicle charging system and an additional charging current of an additional vehicle coupling of the additional charging system exceeding a threshold discharge differential over a predetermined time interval.
 18. A site charging system for charging vehicles at a charging site, comprising: a plurality of vehicle charging systems at the charging site connected via a direct current (DC) bus, each vehicle charging system comprising: a power input port configured to receive input electric power from a power source; a battery configured to receive and store electric power derived from the input electric power received at the power input port; a vehicle coupling configured to receive a charging current from the battery and to provide an electrical interconnect between the vehicle charging system and a vehicle in order to provide the charging current to the vehicle; an inter-charger connection communicatively connected to the battery and to the DC bus to provide DC power to the DC bus and to receive DC power from the DC bus; and a system controller comprising one or more processors configured to control charge transfer between the battery of the vehicle charging system and one or more additional batteries of one or more additional vehicle charging systems of the plurality of vehicle charging systems via the DC bus; an external battery connected to the DC bus and configured to provide DC power to the DC bus and to receive DC power from the DC bus; and a centralized management system communicatively connected to the plurality of vehicle charging systems via an electronic communication connection, comprising one or more processors configured to: determine occurrence of a triggering condition for charge transfer between the respective batteries of a first vehicle charging system and a second vehicle charging system of the plurality of vehicle charging systems via the DC bus; in response to determining occurrence of the triggering condition, control (i) the first vehicle charging system to provide DC power to the DC bus from the battery of the first vehicle charging system and (ii) the second vehicle charging system to charge the battery of the second vehicle charging system using the DC power from the DC bus; determine occurrence of a second triggering condition for an additional charge transfer between the external battery and the respective batteries of one or more vehicle charging systems of the plurality of vehicle charging systems via the DC bus; and in response to determining occurrence of the second triggering condition, control the one or more vehicle charging systems to effect the additional charge transfer based upon the second triggering condition by either (i) providing DC power from the respective one or more respective batteries to the external battery via the DC bus or (ii) receiving and charging the one or more respective battery with DC power from the external battery via the DC bus. 